Mixer



R. WALTON May 8, 1951 MIXER Filed July 6, 1948 INVENTOR: 1Q Malian Patented May 8, 1951 UNITED STATES ATENT OFFICE 3 Claims.

This invention relates to mixing machines for mixing concrete, and the like, and more particularly to means for insuring free delivery of the aggregate to the mixing drum and free discharge of the mixed concrete from the drum.

During the operation of concrete mixing machines, the materials to be mixed are placed in a hopper from which they are fed into the rotary mixing element or drum, which usually consists of a barrel-like structure having vanes or blades for agitating the materials to admix the same. The concrete mixed in the element is commonly discharged through a duct which serves to direct the concrete to desired areas, particularly when the machine is mounted on a motor truck, or other mobile unit. It has been determined that the materials being fed into the mixing drum and the concrete discharged therefrom have the tendency to compact, thus forming solid masses which cannot readily move through the hopper and duct. For this reason it is customary to strike the hopper and duct in order to dislodge masses or the material, or mixed concrete, from the walls thereof, and this operation must be repeated often in order to efiect a free and continuous flow of the aggregate.

It is the primary object of my invention to avoid such difficulty by providing automatic means for continuously vibrating both the hopper and duct, so as to prevent the accumulation or massing of the material therein, which otherwise might impede the free movement of the material to and from the mixing mechanism.

Another object of the invention is to provide vibrating means which is extremely simple, yet

highly efficient in performing its intended function, this means consisting of small pneumatic hammers mounted on the hopper and discharge duct and operated continuously from the usual source of compressed air on the truck.

Another object is to provide vibrating means which can be inbuilt into the concrete mixer unit during manufacture thereof, or readily applied to existing units without altering the structure thereof.

Further objects of the invention are set forth in the following specification which describes a preferred embodiment of the vibrating means, by Way of example, as illustrated by the accompanying drawing. In the drawing:

Fig. l is a side elevational view of a concrete mixing unit adapted to be mounted on a motor truck, or other vehicle; and,

Fig. 2 is a longitudinal sectional view through flows through a stationary chute or spout .11 into the hopper, illustrating the vibrating means mounted thereon.

Referring to the drawing in detail, Fig. 1 illustrates a concrete mixing unit 5 which is adapted to be mounted on a truck, not shown. The mixer 5 includes a framework 6 having bearings for rotatably supporting a rotary drum 1 of generally frusto-conical shape, the drum being arranged with its axis inclined upwardly toward the rear end of the truck. The drum 1 has helical vanes 8 therein which agitate the materials to mix the same during rotation of the drum. The mixing machine also includes a power unit 9 for rotating the drum 1 and a water tank Ill.

The materials, such as sand, stones, and cement, are inserted into a hopper 15 in the usual way, and flow downwardly through the opening or mouth at the small rearward end of the drum 1 to be mixed within the drum. Water is supplied to the interior of the hopper l5 through a line It (Fig. 2) which is connected to the tank Ii]. After the materials have been mixed within the drum '1, the mixture is discharged through the open end of the drum 1 in the usual manner, and

a pivoted chute l8, which can be swung to desired angles to cause the mixture to be delivered to the required areas ofthe roadway, or other structure being made.

It is well known that during operation of concrete mixers of this conventional type the materials which are deposited in the hopper H5, in either loose relatively dry form or in a wet condition, tend to cling or adhere to the sides of the hopper, and thus the free flow of the materials to the mixing drum is impeded. Due to this condition, it is customary to violently strike the side of the hopper so as to dislodge the materials, and thus cause them to slide through the hopper l5 into the mixing drum 1. This condition is not only exasperating but results in loss of time and improperly mixed concrete. concrete delivered to the chute l8 likewise adheres to the sides of the chute and is usually freed by manually rapping the chute.

It is the aim of my invention to avoid such a condition by providing means for automatically and continuously vibrating the hopper I5 and the chute It, so as to maintain continuous and unimpeded fiow of the materials to be mixed and also the wet mixed concrete. This means consists of pneumatically operated vibrator devices 20 :andZD. Since each device 20 or 20 is identical and mounted in a similar way, only the Moreover, the mixed 3 device 20 connected to the hopper l5, and illustrated in Fig. 2, will be described in detail.

The vibrator device 20 consists of a cylinder 2| having end plates 22 and 23 in the form of screw caps, screwed into the ends of the cylinder, and a piston 24 reciprocable in the cylinder. The cylinder 2! is rigidl connected to an angular bracket 25, which is preferably welded to the side of the hopper [5. The cylinder 2! has an inlet port 26 which is adapted to receive compressed air from a, tank 21 on the mixing unit through a flexible line 28, a manually operable valve 29 being included in the line. The interior of the cylinder 2| has three longitudinal grooves 30, 3|, and 32, the groove 30 being in communication with the inlet port 26. The piston 24 has a pair of peripheral grooves 35 and 36 which are adapted to register, respectively, with the grooves 30, 3|, and 30, 32, when the piston is at the opposite ends of its reciprocatory movement.

Assuming that the piston 24 is in the lowermost position shown in Fig. 2, when compressed air is introduced through the inlet port 25, the air flows from the groove 38, through the peripheral groove 35 and groove 3|, into the lower end of the cylinder 2| to force the piston rapidly upward until its upper end strikes the end plate 23. At this instant, the peripheral groove 36 registers with the grooves 30 and 32 to permit the air to enter the upper end of the cylinder, thus forcing the piston downwardly until its lower end strikes the lower end plate 22. In this manner the ends of the cylinder are alternately and rapidly struck with considerable impact to cause vibration of the cylinder and the hopper IE to which it is connected, the result of this vibratory movement being to dislodge materials from the walls of the hopper and maintain free flow thereof into the mixing drum 1. This vibration continues as long as the valve 29 remains open.

The vibrator device 23 is similarly connected to the chute l8, and is operated in a like manner by compressed air flowing through a line 28" and valve 29', this device functioning to continuously vibrate the chute and insure free, unimpeded delivery of the mixed concrete. Thus,

both the materials to be mixed and the mixed concrete are caused to flow freely into the drum and through the delivery chute.

While I have herein shown and described the invention, as embodied in a preferred form of construction, and the vibrator devices mounted in a preferred manner, it is to be understood that various modifications might be made therein without departing from the spirit or scope of the invention. Consequently, without limiting my-' self in this respect, I claim:

1. In a concrete mixing machine having a rotary mixing drum, hopper means defining an inlet passage through which material to be mixed 6 is introduced into said drum, and discharge duct means defining an outlet passage through which the mixture is discharged from said drum: a first pneumatic vibrating means including a cylinder fast on said hopper means and extending parallel thereto and a piston reciprocable in said cylinder; and a second pneumatic vibrating means including a cylinder fast on said duct and extending parallel to said duct; and means for introducing fluid alternately into the ends of each cylinder to vibrate said pistons so as to agitate said material during its introduction and said mixture during its discharge.

2. In a concrete mixing machine having a rotary mixing drum for mixing concrete and a discharge duct through which the mixed concrete is discharged: a bracket formed integrally with said duct; a cylinder element fast on said bracket with its axis extending parallel to said duct; a piston reciprocable in said cylinder element; and means for introducing fiuid alternately into each end of the cylinder element to reciprocate said piston in the direction of discharge of the mixed concrete so as to vibrate said bracket and duct and thus agitate the mixed concrete to insure free flow through said duct.

3. In a concrete mixing machine having a rotary mixing drum for mixing concrete, a hopper for containing a supply of material to be mixed and feeding the material to said drum, and a discharge duct through which the mixed concrete is discharged: a source of compressed air; a first cylinder fast on said hopper and extending parallel to thedirection of feed of the material through the hopper; a first piston reciprocablein said cylinder; a first air line extending from said source to said cylinder; valve means in said first cylinder for directing the air alternately to opposite ends of the same so as to reciprocate said first piston and thus vibrate said hopper; a second cylinder fast on said discharge duct and extending parallel to the direction of discharge of the mixed concrete through the duct; a second piston reciprocable in said second cylinder; a secmid air line extending from said source to said second cylinder; valve means in said second cylinder for directing air alternately to opposite ends of the same so as to reciprocate said second piston and thus vibrate said duct; and flow valve means selectively operable for controlling the flow of air to either saidfirst or second cylinders, or to both.

ROY WALTON.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 486,486 Gates Mar. 11, 1924 1,996,209 Lichtenberg Apr. 2, 1935 2,l76;893 Engeby Oct. 24, 1939 2,223,307 Pacchetti et al'. Nov. 26, 1940 

